Fc (Unix)

Last updated
fc
Developer(s) Various open-source and commercial developers
Operating system Unix, Unix-like
Platform Cross-platform
Type Command

fc is a standard program on Unix and Unix-like operating systems that lists, edits and re-executes commands previously entered to an interactive shell. Its name is an initialism for "fix command". [1] It is particularly helpful for editing complex, multi-line commands.

Contents

The fc command is required to be an "intrinsic" utility by POSIX [2] , and as such is implemented as a builtin in the Bash, Zsh, and Almquist shells.

Invoked with no options, fc will open a text editor, allowing the user to modify the last-run command. Upon exiting the editor, the modified command is executed in the current shell. Various other command-line options are supported, allowing quick substitutions, repetition or modification of a specific command from the session history, or a range of commands from the history.

Examples

When invoked with the -l flag, fc will list recent lines from the session history (the last 16 lines by default in the Bash shell [3] ):

$ fc-l 1  pwd2  whoami3  ls4    ls -a

When invoked with -s PATTERN, fc will re-run the most recent command matching PATTERN:

$ fc-sls ls -a.  ..  .bash_logout  .bashrc  .profile

Though, more powerfully, -s enables inline substitution:

$ lsfloder# user typo$ fc-sflod=fold# revise and re-run with correctionls folder

Invoking fc with no arguments edits the last command executed with the user's preferred text editor. Upon exiting the editor, the modified command will execute in the current shell. [4]

$ fc# change 'ls -a' to 'ls -la' in editor and exitls -latotal 20drwxr-x--- 2 user user 4096 Apr 22 15:38 .drwxr-xr-x 1 root root 4096 Apr 22 15:38 ..-rw-r--r-- 1 user user  220 Apr 22 15:38 .bash_logout

The editor to be used can be specified with the -e option; otherwise it is read from the value of the FCEDIT environment variable [5] , or, in some shells, EDITOR [3] [6] [7] , with a fallback to vi or ed.

It is also possible to edit and re-invoke a range of commands from the history:

$ fc-l 1  pwd2  whoami3  ls4    ls -a5    ls -la$ fc12# specify start and end history entries, separated by whitespacepwd/home/userwhoamiuser

See also

References

  1. "IEEE Std 1003.1-2024 - fc § Rationale". pubs.opengroup.org. Retrieved 2025-04-22.
  2. "The Open Group Base Specifications Issue 8 (IEEE Std 1003.1-2024) - fc § Application Usage". pubs.opengroup.org. Retrieved 2025-04-22.
  3. 1 2 "Bash History Builtins (Bash Reference Manual)". www.gnu.org. Retrieved 2025-04-22.
  4. "Fix history: Edit the last bash command". 5 January 2020.
  5. "IEEE Std 1003.1-2024 - fc § Environment Variables". pubs.opengroup.org. Retrieved 2025-04-22.
  6. "The Z Shell Manual § 15.6 Parameters Used By The Shell". zsh.sourceforge.io. Retrieved 2025-04-22.
  7. "dash FreeBSD manual page § "Builtins"". man.freebsd.org. Retrieved 2025-04-22.